High vanadium alloys



United States Patent 3,449,119 HIGH VANADIUM ALLOYS Frederick C. Holtz, Jr., Evanston, Ill., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy No Drawing. Filed Nov. 15, 1966, Ser. No. 594,627 Int. Cl. C22c 1/02, 27/00; C21d 1/78 US. Cl. 75-134 9 Claims ABSTRACT OF THE DISCLOSURE A vanadium-columbium-titanium alloy with small percentages of silicon and carbon characterized by high tensile strength between 320 F. and 2000 F.

This invention relates to a vanadium base alloy containing columbium and titanium with small additives of silicon and carbon.

Previous vanadium alloy studies had indicated that vanadium-columbium base compositions had attractive short-time strength properties in the -1800 to 2400" F. range. Limited testing at temperatures as low as 452 F. (259 C.) showed these materials to be unusually strong and ductile. The present work was aimed at producing dispersion-strengthened compositions which would not only have good cryogenic properties but also good retention of strength at temperatures above that at which the nickel and cobalt base superalloys are used. Because of their comparatively low melting point, these alloys were not expected to be as strong as columbium, molybdenum, tantalum or other refractory alloys at temperatures in excess of 2400 F. However, the excellent fabrication characteristics and the ability to form reliable silicide oxidation-protective coatings indicate high potential for use over a wide range of temperatures. The development of space craft finds a need for alloys which will retain their strength at both low and high temperatures.

The object of the present invention is to provide an alloy or group of alloys which excell in fabricability, ductility and high strength over a range from -320 F. to at least 2000 F.

Another object of the present invention is to provide a group of alloys which will have high strength at extremes of low and high temperatures and which will form oxidation-protective coating.

Still another object of the present invention is to provide a vanadium based alloy containing columbium and titanium and additives of silicon and carbon.

Other objects will be apparent from the subsequent disclosures and appended claims.

The alloys which are the subject of this invention are based on a V-Cb-Ti system with small additives of Si and C.

Materials used:

In the experimental procedures a single lot of vanadium melting stock was used with the following analysis of the V.

3,449,] 19 Patented June 10, 1969 Oxygen 0.040 Nitrogen 0.028 Carbon 0.040 Hydrogen 0.004 Iron 0.050 Silicon 0.020

Percent Columbium 15-20 Titanium 5-10 Silicon 0.25-0.75 Carbon 0.75-0.25 Vanadium Remainder to make INGOT PREPARATION (1) Melting All of the compositions were prepared by nonconsumable-electrode arc-melting under a highly purified argon atmosphere. Ingot weights ranged from to 200 grams, depending on density, and the ingots were inverted and remelted five times to insure good homogeneity. These ingots were approximately 0.4 in. thick by 2.4 in. in diameter.

(2) Thermal homogenization The arc-melted ingots were thermally homogenized in a tantalum-element resistance-heated furnace. These heat treatments were conducted under vacuum (10- torr or better) or in argon which was purified by passing the gas through hot titanium sponge and a liquid nitrogen trap. After heating for the desired length of time, the ingots were lowered from the hot zone and cooled by a stream of flowing argon at a rate of approximately 400 F./min.

(3) Ingot fabrication The initial ingot breakdown for nearly all of the alloys Was achieved by hammer forging. The ingots were jacketed in 0.030 in. thick stainless steel, then evacuated. Hammer forging was done at 2350-2400 F. on a mechanical drop hammer. Reductions in thickness of 30 to 40% were used to obtain a final forged thickness of 0.25 to 0.30 inch. The more diflicult-to-work alloys required reheating to achieve this reduction. After forging, the jackets were stripped and any edge or surface cracks were removed by grinding. The conditioned ingots were then cold-rolled, in most cases with intermediate vacuum annealing, to sheet ranging in thickness from 0.004 to 0.027 in. Rolling reductions were initially 10% per pass, although smaller reductions were used when the sheet was less than 0.030 in. thick. A list of representative compositions together with the processing methods and results of ingot fabrication is presented in Table I.

3,419,119 3 4 TABLE I.VA IADIUM ALLOY FABRICATION DATA Density,

Composition, wt. percent lb./in. Fabrication Procedure a Results V-l5 (Db-10 T105 Si-0.15 C 0.22 gIFi-ogto-agringrf gooisgeet, 0.009 in. 2, rac e V-20 Cb-Tl-025 $101 0. 2a Good Sheet, 0027 in.

Cracked.

V-20 Cb- Ti0.5 Si-0.1 C 0. 23

V-20 (lb-7.5 Ti-0.5 Si-0.15 C 0.22 HF-C R-Ann-G 0.22 HF-CR-Ann-CR Good sheet, 0.027 in. Good sheet, 0.009 in. Good sheet, 0.025 in.

V-20 013- Ti-0.5 S1-0.05 O 0 22 HF-CR-Ann-CR Good sheet, 0.008 in. V 20 Cb-lO Ti-0.5 51-0075 0. 22 HF-CR-A1'111CR Good sheet, 0.010 in. V-20 Cb-l0 Ti-0.5 Si-O C 0 22 HF-GR-Ann-CR Good sheet, 0.000 in. V- (lb-10 Ti-0.4 S102 O 0 22 HF-CR Severe edge cracks at 0.04 in. V-20 (lb-10 Ti-0.5 Si-0.2 G 0 22 HF-CR-Ann- Good Sheet, 0.009111. V-20 Cb-lO Ti-0.7 Si-O.l5 0.... 0.22 lrzlg-CRbArgi-HF C 12oE1 1 2, 0 x ensive erac ing a 0.2 in. CW0 512-25 0 22 TH 2, 300 F.-HF-CR-Ann-CR Moderate edge cracking at 0.03 in. V-60 Cb-l Ti 0. 27 CR-Ann-CR Good sheet, 0.027 in.

u TH=Tl1ermal homogenization, 3 hr. at 2,800 1 X, 4 hr. at 2,300 and 2,600 F.; HF=hammer forge; Ann=Vacuum anneal, hr. at 2,000 to 2,400" F.; CR=Cold roll.

RECRYSTALLIZATION at temperatures from 1200 to 1600 F. Most of the aged Alloys based on V-Cb-Ti were evaluated for recrystal- 20 Specimens were evaluated by room temperature q lization behavior. Sheet specimens were cold-rolled to 1653- Table III Presents data for three alloys contamlng reductions in thickness of about 80%, then annealed in Varylng amounts of Silicon and carbon- TABLE III.-AGING RESPONSE OF HIGH-VANADIUM ALLOYS V-20 Cb-10 Ti-0.5 Si-0.15 C V-20 Cb-10 Ti-0.7 S1015 C V-20 Cb-10 Ti0.5 51-02 C Elong., Elong., Elong Treatment UTS, p.s.l. percent UTS, p.s.i. percent UTS, p.s.i. percen As cold rolled 181,000 1.5 187,000 186,000 1. 107, 000 2. 5 203, 000 a. 0 197, 000 a. 0 199, 000 3. 0 214, 000 2. 5 103, 000 2, 0 104, 000 3.0 202, 000 202,000 4. 5 208, 000 3. 0 213, 000 5. 0 201, 000 185, 000 4. 5 190, 000 7. 0 180,000 5. 0 1,300 F.-1 hr 187,000 7. 0 200,000 6. 5 192,000 5. 0 1,300 1 .4 hr 130, 000 8.0 189,000 6.0 183,000 7. 0 2,000 hr. 123, 000 24. o 117, 000 17. 0 121, 20. 5

a Cold rolled to 0.008 in. prior to indicated treatment. b Broke outside of gage marks. a vacuum for 30 minutes at temperatures in the 1600- Solution-annealed specimens of two V-Cb-Ti base a1- 2400 F. range. The extent of crystallization was deterloys were also aged and evaluated for room-temperature mined by metallographic observation, and hardness meastensile properties. Solutionizing was done for min. at

urements were also taken on the annealed specimens. Ta- 40 2000 F. followed by water quenching. Aging at 1100 ble 11 lists the lowest temperatures at which complete and 1200" F. produced the following results for the alloy crystallization occurred after 30 minutes annealing treat- V-Cb-lOTi-0.5Si-0.075C.

ments conducted at 100 F. intervals. Hardness data for Ultimate the fully crystallized specimens are also included. Tens mom 4 Strength tign E RYSTALLIZATION AND HARDNDSS DATA TABL H REC FOR VANADIUM ALLOYS Treatment 13.5.1. percent Recrystallization Hardness, 2,0000 F' 40 ml 1241000 19 2,000 F.40 m1n., W.Q,.; aged 1,l00 F. 24 hr- 148, 000 13 Cmmsitmm Percent Temp o VPN 2,400 152-40 min., W.Q.; aged 1,200F.: 4 hr 135,000 15 3' 8 801 1 1 0 s 0 1 5 o' H88 323 s 1 1 b d f n vzocb 101 05s .5 .5 iimi ar resu ts were 0 taine or e ii- 1,00 280 321, 3?, 2 ,35 1,5100 269 0.05C alloy. These data indicate that solutlon annealing V-20 010-10 T105 81-0- 0-- 1,800 289 followed by aging does not produce strength levels as 0 2 v 20 Ch 10 T1 0 751015 0 1 7 0 93 high as those obtalned by cold-rolling followed by agrng,

although the tensile elongations are higher. AGING RESPONSE CRYOGENIC TENSILE PROPERTIES Studies of aging behavior were carried out on selected alloys of the V-Cb-Ti system. Sheet specimens were fully The alloys were tested for tensile strength at temperaannealed for 30 minutes at 2000 F. The specimens were tures as low as that of liquid nitrogen (320 F.). The cooled from the annealing temperature at a rate of about tested specimens had a A by 1 in. gage section, and were 250 F./nn'n. to room temperature, then cold-rolled to tested at a strain rate of 0.005 in./in./min. The results reductions in thickness of 60- Aging was conducted are shown in Table IV.

TABLE IV.TENSILE DATA FOR VANADIUM ALLOYS AT LIQUID NITROGEN TEM' PERATURE (320 F.)

Density Ultimate Total Corrected Tensile Elongation, Strength, Composition, wt. percent Treatment Strength, p.s.i. percent UTS/(lbJinJ) Annealed 205, 000 26. 2 919, 000 V-20 Cb-lO Ti-0.5 51-015 C Aged 1,200 F., 24 111. 270,000 14. 2 1, 210, 000 Aged 1,300 F., 1 111'- 275, 000 12. 0 1, 3, 000 Annealed b 205, 000 23. 8 8, 000 V-20 Cb-l0 T1-0.5 51-02 C Aged 1,200 F., 24 hr 280, 000 11. 8 1, 267, 000 Aged 1,300 F., 1 hr- 275, 000 12. 8 1, 245, 000

Annealed b 210, 000 25. 8 942, V'20 Cb-lO Tl-O? Si-0.15 C Aged 1,200 F., 14 111.... 275, 000 11. 7 1, 233,000 2 31 88 182 23 3888 1%" 1 ge ,2 r .2 ,145, 000 V Ch 10 M C "{Aged 1,300" 1 2 hr--- 259, 000 14. 8 1,080,000

a Aging treatments after 60-80% reduction by cold rolling. b Fully reerystallized2000 F., 30 min.

TABLE V.-ROOM-TEMPERATURE TEN SILE DATA FOR FULLY ANNEALED VANADIUM ALLOYS Ultimate 0.2% Ofiset Density Tensile Yield Elonga- Corrected Stregnth, Strength, tion, Strength,

Composition, wt. percent p s.i. p.s.i. percent UTS/(lbJinfi) V-15 Cb-lO Tl0.5 Si0.15 C 111, 000 92, 500 22 506, 000 V-20 Cb-5 Ti0.25 Si-0.1 C 108, 000 92, 000 25 476,000 V-20 (lb-5 Ti-0.5 Si0.1 C- 116, 000 99, 500 27 511, 000 V-20 (lb-7.5 Tl0.5 Si-O.15 C. 114, 000 96, 000 21. 5 509,000 V-20 Cb-IO Ti-0.375 Si0.075 C 114, 102, 000 24 512, 000 V-20 (Db-10 Ti0.5 Si0.05 C 114, 500 102, 500 20 520, 000 V-20 (Db-10 Ti0.5 Si0.075 O 116, 000 102, 500 18 528, 000 V-20 Cb-10 Ti0.5 Si0.15 C 123, 000 113,000 24 552, 000 V-20 Cb-lO Ti0.5 Si0.2 0-- 121, 000 102, 500 20. 548, 000 V-20 Ola- 'Ii-0.7 Si0.15 C 117, 000 102,000 17 525, 000 V-20 Cb-lO Ti0.75 Si-0.15 C b 132, 000 120,000 17 594, 000

a Vacuum annelaed 2,000 F., min., unless otherwise noted. b 2,200 F.10 min.

ROOM TEMPERATURE TENSILE PROPERTIES Tests conducted at room temperature are shown in Table V. The results in Table V were obtained on 0.008 to 0.025 in. thick sheet which was cooled from the annealing temperature to below visible heat at a rate of approximately 250 F./min. Both carbon and silicon strengthened the V-20Cb-l0Ti base to a moderate degree. The strongest alloy, V-20Cb-10Ti-0.75Si-0.15C, had a density corrected strength of 594,000 in. This high strength was due to the high silicon content and possibly to the fact that the 10-min, anneal at 2200 F. produced retention of more strengthening elements in solid solution than was obtained at 2000 F. annealing temperature used for most of the alloys. The effects of various annealing treatments on the composition V-20Cb-10Ti- 0.5Si-0J075C are shown below:

Ultimate Tensile Elonga- Strength, tion, Treatment p.s.i. percent 1,800 F., 10 111111., 0001 at 250 FJmin 117, 000 21 2,000 F., 30 min., cool at 250 F./1I1111 116, 000 18 2,000 F., min., water quench 124, 000 19 ELEVATED-TEMPERATURE TENSILE PROPERTIES COMPARATIVE DATA A comparison of the tensile strengths of the experimental alloys with those of commercial cryogenic and refractory materials shows the temperature ranges over which the vanadium alloys demonstrate attractive properties. Vanadium alloys compare favorably with the crygenic alloys (stainless steel and titanium base alloys) and the vanadium alloys do not exhibit the sharp decrease in strength about 1200 F.

The vanadium alloys, enriched with silicon and carbon exhibit excellent fabricability. They are as good as stainless steel at low temperatures and surpass the nickel-base alloys at all test temperatures.

What is claimed is:

1. An alloy having high tensile strength at temperatures between 320 F. and 2000 F. consisting essentially of 15-20% Cb, 5l0% Ti, 0.25-0.75% Si, 0.0750.25% C-remainder V.

2. An alloy according to claim 1 in which the specific proportions are 20Cb-lOTi OJSSi-O.ISC-remainder V.

3. An alloy according to claim 1 in which the specific proportions are 20Cb-10Ti-0.375Si-0.75C-remainder V.

4. An alloy according to claim 1 in which the specific proportions are 20Cb-10Ti-0.5Si-0.075C-remainder V.

5. An alloy according to claim 1 in which the specific proportions are 20Cb-1OTi-O.5Si-0.05C-remainder V.

6. An alloy according to claim 1 in which the specific proportions are 20Cb-10Ti-0.7Si-0.ISC-remainder V.

7. An alloy according to claim 1 in which the specific proportions are 20Cb-7.5Ti-0.ISC-Iemainder V.

8. An alloy according to claim 1 in which the specific proportions are 20Cb-l0Ti-0.5Si-0.ISC-remainder V.

9. An alloy according to claim 1 in which the specific proportions are 20-C-b-10Ti-0.5Si-0.2C-remainder V.

TABLE VL-ELEVATED-TEMPERATURE TENSILE DATA FOR HIGH-VANADIUM V-Cb-Ti BASE ALLOYS Ultimate Density- Test Tensile Elonga- Corrected Temp Strength, tio Strength, Composition, wt. percent Treatment p.s.l. percent UTS/(lbJinfi) Annealed 2,000 F., 30 mm. 1,800 30, 000 09 130, 000 V-20 Clo-10 Ti0.5 s1-0.05 o Annealed 2,000" F., 30 min., WQ 1, s00 59, 000 26 266, 000 Ann i 3333 3"33$n"w 3'33 3333 33 e ae 0 259 000 CH0 C "{Annealed 2:000 F1 30 nn'n. 2,000 27,000 79 1231000 3 80% i 333 33 333 133 333' 333 o 81-015 0 Annealed 2,000 30 min 1,800 52, 300 34 234, 000 .do. 2, 000 40, 000 70 179,000 Cold rolled 80% 1,800 200 26 150, 000 v-2o Cb-lO T1-.4 s1-0.2 0 Annealed 2,000" F., 30 min. 1, s00 59, 000 34 207, 000 olli 'ii'ri""' i'i200''i"fl 3' 333 133' 333 3 833' 333 0 r0 e age rs 1 V 20 Cb T1415 C "{Annelaed 21000" 1 .1 30 min. 1,800 ,800 28 280,000 v-20 Cb-10 T1-0.7 Si0.15 0 Cold r ll 1,800 25, 500 114, 000

Cooled at 250 FJmin.

References Cited UNITED STATES PATENTS 2,886,431 5/1959 Smith et al. 75-134 3,038,798 6/1962 Berger et al. 75-174 3,136,631 6/1964 Wlodek 74-134 RICHARD O'. DEAN, Primary Examiner.

UNITED STATES PATENT OFFICE 5 CERTIFICATE OF CORRECTION Patent No. 3,449,119 Dated June 1 1 69 Inventr(s FREDERICK C. HOLTZ, JR.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 7, line 2, after "7.5Ti-" insert ollmtU Aliu SEALED DH! 3 0 me (SEAL) .Attest:

Fl tcher, I EdwardM WILLIAM E- 'SOHUYLER, JR. Attesting Offic r Commissioner of Patents 

